Archived from groups: alt.tv.tech.hdtv (
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In article <MPG.1b1f0bca66244a57989707@news.gwtc.net>,
Ron Malvern <rmlvrn@nospam.com> writes:
> In article <c93jum$2i5b$1@news.iquest.net>, John Dyson toor@iquest.net
> says...
>
>> In article <MPG.1b1ef140da52bf36989706@news.gwtc.net>,
>> > In vertical static chroma resolution, 720p rates 180, 1080i rates only
>> > 140.
>
>> That is a slight difference, when comparing the following:
>> 720p diagonal is 230 vs. 1080i diagonal is 260.
>
> In what? Chroma? Luma? You don't say. Be specific, John. For an
> engineer, you are incredibly sloppy with details.
>
The context was obvious if you also look at the table. I assumed that
you could maintain context... Of course, maybe the large number
of discrete data items can cause confusion. (Alot like moving
objects on the screen
.) Perhaps all of the details within the
field of view might be confusing to you?
Remember also: if you maintain all detail in moving objects (allow temporal
aliasing), then movement doesn't even look natural. Film productions are
generally recorded with averaging over the entire sampling interval. There
is a natural motion smear to 'natural' perception. If you allow temporal
alasing, the movement tends to be less natural (and wierd strobing
effects become more troublesome.)
So, on filmed material, moving items tend to have less 'detail' because
of averaging over the exposure time. Some video cameras can set the
'exposure time' to be different than the frame rate -- but that is
more of a utility for special purposes (e.g. sports freeze frame or
flicker reduction or other purposes.)
>
>
>> Also, in the 'target spec' the difference between 1080i and 720p is
>> reversed.
>
> So?! The target spec doesn't matter.
>
Yes it does -- refer to the 'Note 1' that describes their concept
of measurement error (or equivalent.)
>
> The test spec is what matters.
>
And the differences were in the order of measurement error.
>
> Any
> fool can say he want x and y performance from a given piece of equipment.
>
You are being abusive. A fool with an agenda would ignore the concept of
measurement error...
>
> We're not talking statistics here, John. We're talking test results.
>
All tests have measurment error, Ron. The individuals who collected
the data apparently believed that there was error in their technique
or in their measurements.
>
> But if you want to make a big deal of that, then the entire ATSC Final
> Technical Report is meaningless
>
Reducing the argument to the absurd. Refer to the differences that
were deemed within measurement error. Note that the 'error' in this
context would also include measurement technique issues.
Remember: the significant differences that were outside of
reasonable 'measurement error' showed that 1080i provided more
detail.
>
>> > But since we're talking about moving pictures here, dynamic resolution
>> > with moving images will always be more important.
>
>> Nope -- most detail isn't moving, or MPEG wouldn't work!!!
>
> But the part of the image at the center of attention, faces, bodies, etc.
> are moving all the time.
>
However, the human visual system cannot deal with very much moving detail.
Also(side issue), moving image material that has been properly
exposed (to minimize temporal aliasing) will naturally have smear
due to movement.
Using your argument, you wouldn't care to keep a book still while
reading it -- because you could obviously track the vibrating book!!!
Not!!! (Hint, I have a movement disorder, and can attest to the
difficulty of tracking a moving page of text -- a prototypical
high detail image.)
Mostly, you'll easily see the gross details when something is moving.
You won't see all of the small little precise details (think about a
moving page of written text. Your eyes won't process the detail as well
as if it was still.)
>
>> Take a look
>> at the typical TV show... Detail isn't typically moving!!! If your
>> claim is true, the MPEG wouldn't work. Most detail in video and
>> movies is unchanging...
>
> Gee John, you mean all that stuff on the screen in the movie theatres and
> on television was just standing still all these years!
>
Most of the detail isn't moving, or MPEG-type interframe
compression wouldn't work. It appears that you are using semantics
to justify your incorrect argument...
Again, static detail rendition is more important for the perception
of sharpness. You CAN track moving objects, but your detail perception
is necessarily reduced (otherwise, you wouldn't need to keep books
still while reading them!!!)
John